Do the species of management concern share attributes that distinquish them from other members of the nongame bird community? To answer this question, the distribution of listed species in various guilds and attribute categories is compared with the distribution of all other nongame bird species. Specifically, the following paragraphs compare the BBS guilds of Peterjohn and Sauer (1993), the foraging guilds of DeGraaf et al. (1985), the life-history traits of Ehrlich et al. (1988: xiv-xxiii), and the major taxonomic categories of the American Ornithologists' Union (1983).
(1) BBS Guilds. (a)Nesting Habitat.--Listed species are not proportionally distributed among the five nesting habitats (P < 0.01). Species in the grassland-nesting guild are over-represented (P < 0.01), while wetland and open water, successional-scrub, woodland, and urban guilds occur in about the proportions expected (P > 0.05). (b) Nest Type.--Species of concern are distributed among the cavity nesting and open-cup nesting guilds in about the proportions expected (P > 0.05). (c) Nest Placement.--Species in the ground and low-nesting guild are over-represented on the list (P < 0.01), while those in the mid-story and canopy nesting guild are under-represented (P < 0.01). (d) Migration Status.--Listed species are not proportionally distributed among the three migration status categories (P < 0.05). Neotropical migrants are over-represented (P < 0.05), permanent residents are under-represented (P < 0.05), and short-distance migrants occur in about the proportion expected (P > 0.90).
(2) Foraging Guilds. (a) Foraging Substrate.--Species of concern forage on at least 12 of the 20 wetland substrates and all 5 of the terrestrial substrates of DeGraaf et al. (1985). Listed species do not forage proportionally among the three major substrates: wetland, terrestrial, and air (P < 0.05). Wetland-foraging species are under-represented (P < 0.05), while terrestrial- and aerial-foraging species occur in about the proportions expected (P > 0.05). (b) Food Type.--When classified according to 10 major categories of food eaten, the distribution of listed species does not differ from that of all other nongame bird species (P > 0.05).
(3) Life-History Traits. (a) Clutch Size.--Distribution of clutch sizes of species of concern does not differ from that of the other members of the nongame bird community (P > 0.95). (b) Nest Location.--Listed species are proportionally distributed among the eight major nest location-types (P > 0.10), with the exception that ground-nesting birds are somewhat more abundant than expected (P < 0.10). (c) Nest Type.--Distribution of listed species among the nine major nest types is proportional to the expected distribution (P > 0.10). Species that lay eggs in situations in which they are exposed to visual predators were not more likely to be listed than species that lay eggs in protected situations (P > 0.10). (d) Breeding-Season Diet.--Listed species are proportionally distributed among the eight major breeding-season diet categories (P > 0.25). (e) Chick Development.--Listed species are proportionally distributed among the four chick-development categories (P > 0.10).
(4) Major Taxonomic Categories. Listed species are not proportionally distributed among the major taxonomic groupings (P < 0.01). The list contains higher-than-expected numbers of herons and non-harvested waterfowl (P < 0.10), diurnal raptors (P < 0.10), rails (P < 0.01), and sparrows (P < 0.05). Pelicans and related species (P < 0.05), and corvids and parids and related species (P < 0.01), are under-represented on the list. Other taxonomic groups occur in about the proportions expected (P > 0.10). Passerines and non-passerines are proportionally represented among the listed species (P > 0.50).
To summarize, over-represented guilds or attribute categories include the grassland-nesting guild, the ground and low-nesting guild, and neotropical migrants (sensu Peterjohn and Sauer 1994); ground-nesters (sensu Ehrlich et al. 1988); and herons and non-harvested waterfowl, diurnal raptors, rails, and sparrows (sensu AOU 1983). Under-represented groups include the mid-story and canopy nesting guild and permanent residents (sensu Peterjohn and Sauer 1994); birds that forage in wetland substrates (sensu DeGraaf et al. 1985); and pelicans and related species, and crows and chickadees and related species (sensu AOU 1983).
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